Abstract: A flexible coupling device for sealably connecting together first and second tubular bodies which are subjected to pulsing pressures and to thermal expansion and contraction. The first tubular body includes a first tubular portion having a cylindrical end and a flange and the second tubular body includes a second tubular portion having a planar mounting surface. The flexible coupling device includes a guide ring disposed in telescopic relation with the cylindrical end of the first tubular body, a flexible bellows having first and second attachment ends, a first retaining ring for releasably securing the first attachment end of the flexible bellows to the flange and a second retaining ring for releasably securing the second attachment end and the guide ring to the planar mounting surface of the second tubular portion.